Hydraulic jack



June-I7, 1930. c STUKENBQRG 1,764,859

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Patented June 17, 1930 UNITED STATES PATENT OFFICE LOUIS C. STUKENBORG, OF MEMPHIS, TENNESSEE, ASSIGNOR TO OILDRAULIC LIFT COMPANY, OF MEMPHIS, TENNESSEE, A CORPORATION OF DELAWARE HYDRAULIC JACK Application filed July 9, 1928. Serial No. 291,340.

air under pressure, whereby the piston is elevated from the casing, the piston being provided with a novel construction and arrangement of check valves to automatically stop the piston at a predetermined height, and thus prevent any possibility of the piston moving entirely out of the casing should the supply of air be inadvertently allowed to enter the piston.

Another object of the invention resides in a jack of the above mentioned character provided with a release valve which can be quickly and conveniently manipulated to allow the oil to reenter the piston and thereby permit the latter to gradually lower itself within its casing.

The nature and advantages of the invention will be better understood when the following detail description is read in connection with the accompanying drawings, the in- Vention residing in the construction, combination and arrangement of parts as claimed.

In the drawings forming part of this application like numerals of reference indicate similar parts in the several views and wherein Figure 1 is a vertical sectional view through the jack constructed in accordance with the present invention, and showing the piston wholly arranged within the outer casing.

Figure 2 is a view in elevation and partly in section showing the piston in elevated position.

Referring to the drawings in detail 10 indicates an outer casing in which operates the hollow piston 11. As illustrated in Figure l the piston is spaced an appreciable distance from the Wall and bottom of the casing 10 to define a space for the reception of the oil 12 as it is forced from the piston incident to the elevation of the latter. The casing is provided at spaced points with internal rings 13 to guide and center the piston in its movements, while anadditional ring 14 is ar-. ranged at the top of the casing and utilized for the same purpose.

The piston is adapted to normally contain'a quantity of oil or other fluid, while supported by the head of the piston is a check valve 15 and a release valve 16 for the purpose to be hereinafter described. Supported by the piston 11 at suitable points in its length are check valves 17, while arranged on the bottom of the piston is a similar valve 18, these valves controlling communication between the piston and the outer casing 10. An air supply hose (not shown) is adapted to be coupled with the check valve 15 in the head of the piston to convey air under pressure into the latter when it is desired to elevate the -piston. The load to be lifted is, of course supported by the head of the piston, and when air under pressure is admitted into the latter, the oil or other fluid is forced from the piston through the valves 17 and 18 into the outer casin 10, where upon the piston is elevated as Wlll be readily understood. The piston will continue to rise as long as the compressed air is forced into the interior thereof, but the check valves 17 are utilized as safety valves to prevent the piston from moving entirely out of the casing 10, should the user through inadvertence forget to turn off the supply of air when the plieton reaches a predetermined height. In ot er words the piston 11 will continue to rise in the manner above described until the check valves 17 pass above the upper end of the easing 10, whereupon the piston will stop, as the air entering the piston will then escape to the atmosphere through the check valve 17 as will be readily understood. In view of this fact the check valve 17 can be arranged at any desired location throughout the length of the piston so as to allow the latter to rise to a maximum predetermined height.

For the purpose of lowering the piston I provide the latter with a release valve including a casing 19 supported on the bottom of the piston, While the valve 20 is in the nature of a needle valve, which extends through the entire length of the piston and is provided with a knob or manipulating handle 21 adjacent the head thereof. Manifestly after the piston has been elevated, and it is desired to lower the piston, it is only necessary to open the valve 20 which allows the oil to reenter the piston from the outer casing, during which time the piston will be gradually lowered to its normal position. WVhen the valve 20 is-opened to allow the oil or other fluid to reenter the piston as just described, the valve 16 is opened to permit air in the top of the piston to escape.

While it is believed that from the forego ing description the nature and advantages of the invention will be readily understood, I desire to have it known that I do not limit myself to what is herein shown and, described and that such changes may be resorted to when desired as fall within the scope of what is claimed.

.. WVhat is claimed is:

1. A hydraulic jack comprising a casing, a

hollow piston arranged therein and adaptedto contain oil, a valve in the head of said piston for regulating the admission of air under pressure to the piston, check valves carried by the piston at appropriate points in its length to control communication between the piston and said casing and permit the oil to escape from the piston as the air enters the latter and thereby govern the upward movement of the piston, said last mentioned valves being located to pass beyond the upper end of the casing to permitthe escape of air and thereby automatically stop the piston at a predetermined height, and a valve carried by the piston and controlling communication between the latter and the casing for the return of oil to the piston. I

2. A hydraulic jack comprising a casing, a hollow piston arranged therein and adapted to contain oil, a valve in the top of the piston for admitting air under pressure thereinto, a check valve in the bottom of the piston, similar valves arranged at appropriate points in the length of the piston and establishing com- ,municationbetween the latter and the casing for the passage of oil into the latter under pressure, said valves being located to pass beyond the upper end of the casing to per- LOUIS C. STUKENBORG. 

